Zigzag sewing machine



April 1966 SHINICHI KAWAGUCHI 3,246,619

Z IGZAG SEWING MACHINE 2 Sheets-Sheet 1 Filed Dec. 20, 1962 April 19, 1966 SHINICHI KAWAGUCHI 3,246,619

Z IGZAG SEWING MACHINE 2 Sheets-Sheet 2 Filed Dec. 20, 1962 United States Patent 3,246,e19 ZIGZAG SEWING MAQI-IINE Shinichi Kawaguehi, Suginarni-ku, Tokyo, Japan, assignor to Riccar Sewing Machine 130., Ltd, Tokyo, Japan Filed Dec. 20, 1962, Ser. No. 246,136 4 Claims. (Cl. 112-158) This invention relates to a zigzag sewing machine, wherein the rotation of the main shaft is transmitted to a rotary type bobbin case through a crank rod having a sliding rod member which is annularly engaged with the main shaft and is supported on a crank rod support.

According to one of the known proposals in the past, the rotation of the main shaft is transmitted to the bobbin case through a transmission mechanism comprising plural gears. By means of such a kind of mechanism, the bobbin case may be rotated by the rotation of the main shaft, however, there are disadvantages that the noise of gears is difficult to be eliminated, high technical skill is required for finishing transmission members and assembling operations therefor are troublesome.

According to another known proposal, the main shaft and the lower shaft are respectively provided with several pieces of crank members and by means of the cranks and a proper number of crank rods the main shaft and the lower shaft are connected, thus the rotation of the main shaft is transmitted to the lower shaft to rotate the bobbin case. In this case, noise may be eliminated, however, there are disadvantages that the transmission members are occupying substantial space within the narrow housing of the sewing machine, higher technical skill than the former is required for finishing the transmission members and assembling operations therefor are also troublesome.

According to still another known proposal, the rotation of the main shaft is transmitted to the lower shaft by means of timing belt and chain to rotate the bobbin case. In this case, the assembling operations are simplified and no high technical skill is required for finishing, however, there are disadvantages that the timing will become wrong due to the expansion of timing belt and chain, and the exchange of the same will require troublesome operations.

What are usually demanded in a zigzag sewing machine using a rotary bobbin case are simple construction and simple assembling operations accompanied therewith as well as large amplitude of zigzag stitching.

The objects of this invention'are' to eliminate all disadvantages involved in the various known proposals, to rotate the rotary bobbin case with same or twice the number of revolutions as that of the main shaft by means of a simple construction, thus to obtain a zigzag sewing machine capable of minimizing the skipping of stitches and the change of stitching strain when the amplitude of zigzag stitching is made larger.

These objects may be attained, according to the present invention, by providing a crank rod, a crank support and a rotary pendulum having a sliding member for transmitting the rotation of the main shaft to the lower shaft, within a zigzag machine.

For a more complete understanding of the nature and scope of the present invention, reference may be had to the following detailed description which may be read in connection with the accompanying drawing, in which:

FIG. 1 is a front view of a longitudinal section of the housing of a zigzag sewing machine along a vertical plane including approximately the main shaft.

FIG. 2 is a bottom view showing the interlocking mechanism between the lower shaft and the bobbin case.

FIG. 3 is an explanatory drawing of a roller attached to an end of the crank rod by means of a screw bolt.

FIG. 4 is a cross-section of FIG. 1 along line AA.

FIG. 5 is an explanatory drawing showing the relatittlm of rotations between the main shaft and the lower s aft.

FIG. 6 is an explanatory drawing of the mechanism of the crank rod.

FIG. 7 is an explanatory drawing of the mechanism of the crank rod support.

In FIG. 1 and FIG. 4, 1 is an arm of the sewing machine, to which a main shaft 2 is rotatably attached. 3 is a crank of the main shaft, with which a crank rod 4 is rotatably and annularly engaged.

As shown in FIG. 6, the crank rod 4 comprising an annular portion 5 and a sliding rod member 6, on which end a screw hole 7 is provided for attaching a roller (cf. FIG. 3).

A roller 8 is pivotally attached to the sliding rod member 6 by means of a screw bolt 9 fitted in the screw hole 7.

As shown in FIG. 7, the sliding rod member 6 slidably passes through a guide hole 11 of -a crank rod support 10, and a supporting journal 12 of the crank rod support 10 is rotatably inserted into a bearing 14, which is fixed adjustably to the arm 1 between the main shaft 2 and the axis of the lower shaft 13 by means of a screw 25 (cf. FIG. 4).

15 is a rotary pendulum and fixed to one end of the lower shaft 13, which is rotatably passing through bearings 17, 18 of a bed 16 of the machine. The rotary pendulum 15 is provided with a guide groove 19, in which the roller 3 is slidably engaged.

The screw hole 7 for attaching the roller is so arranged that the central distance between the annular portion 5 of the crank rod 4 and the roller 8 becomes the same as the central distance between the main shaft 2 and the lower shaft 13.

On another end of the lower shaft 13, a larger bevel or helical gear 20 is fixed and meshing with a smaller bevel or helical gear 21 (cf. FIG. 2).

The ratio of the number of teeth between the larger bevel or helical gear 20 and the smaller bevel or helical gear 21 is 2:1.

The mechanism thus constructed of the present invention will be operated as follows:

According to the rotation of the main shaft 2, the crank rod 4 rotatably and annularly engaged with the crank 3 of the main shaft will be operated interlockingly. Then, the sliding rod member 6 of the crank rod 4 will make a sliding motion through the guide hole 11 of the crank rod support :10, which is rotatably inserted into the bearing 14 attached to the arm 1, and the supporting journal 12 will make return motions according to the rotation of the crank 3 of the main shaft.

In this case, as seen from FIG. 5, the roller 8 attached to the end of crank rod 4 will rotate in a direction opposite to the rotation of the main crank 3 while passing the same route as the passage X of the motion of crank 3 of the main shaft.

Since the roller 8 is slidably engaged within the guide groove 19 of the rotary pendulum 15 and the roller 8 will move on the passage X around the central axis of the lower shaft 13, the lower shaft 13 will rotate in an opposite direction to the main shaft 2 and the bobbin case will rotate through the bevel or helical gears.

In this case, however, as shown in FIG. 5, central angles a, {3 are made between two lines connecting the center 0 of the circular passage X of the motion of crank 3 and points of Contact B, C of two tangents A-B, A-C which are passing through the center of the axis of the supporting journal 12.

The tangents A-B, A-C will also contact with the circular passage Y of the roller 8 at B, C, so that central angles a, in the circular passage Y are equal to the above central angles a, B respectively.

Since said tangents and the central line of crank rod 4 will coincide with each other, in case the crank 3 rotates on the major are B-C of the circular passage X, the lower shaft 13 will rotate on the minor arc B-C, and in case the crank 3 rotates on the minor arc C-B, the lower shaft 13 will rotate on the major arc CB'.

Accordingly, when the crank 3 rotates on the minor arc C-B, rotating angle of the lower shaft 13 will become larger than that of the main shaft 2.

In case the time when the crank 3 rotates on the minor are C-B is conformed to thread catching position, in a sewing machine having usual mechanism for needle bar motion of the known crank system, the rotation of the bobbin case will become larger in the amount equal to the difference between the major arc BC and the minor arc CB than the rotation of the main shaft at the time of thread catching when the needle bar 23 is a little higher rising from its lowest position. Namely, the velocity of motion of the bobbin case will become larger than the motion of the needle bar at the time of thread catching, so that the range of thread catching for zigzag stitch amplitude may be made larger.

In short, according to the present invention, the range of engagement between the needle bar and the bobbin case is made larger to make zigzag stitching effectively, by providing a sliding member on a crank rod and by guiding the crank rod with a crank rod support, which is supported in a bearing adjustably attached to the machine arm, thus rotating the lower shaft.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a zigzag sewing machine the combination comprising: a horizontal bed, a needle bar for mounting a needle in vertical position above said bed, a main drive shaft mounted for rotation above said bed, means for rotating said main drive shaft, a needle bar actuating mechanism interconnecting said main drive shaft and said needle bar, said actuating mechanism being operative to cause said needle bar and needle to move through a zigzag stitching sequence wherein said needle successively and alternately lowers at a first point to a thread catching position beneath said base, raises, moves transversely to a second point and lowers at said second point to a thread catching position beneath said base upon rotation of said main drive shaft, means mounting a bobbin to rotate at a fixed position under said bed and beneath said needle bar, and in the plane of needle zigzag movement a bobbin shaft mounted for rotation in a fixed axial position beneath said bed and connected to rotate said bobbin, and motion transfer means connected to permit said main drive shaft to rotate said bobbin shaft, said motion transfer means incorporating a non-uniform motion conversion means synchronously relating the movements of said needle bar and said bobbin shaft in a manner such that said bobbin shaft rotates through a greater are while said vertical needle is in its aforesaid thread catching positions, and through a lesser arc while said vertical needle is in its aforesaid raised positions.

2. In a zigzag sewing machine the combination com prising: a horizontal bed, a needle bar for mounting a .needle in vertical position above said bed, a main drive shaft mounted for rotation above said bed, means for rotating said main drive shaft, a needle bar actuating mechanism interconnecting said main drive shaft and .said needle bar, said actuating mechanism being operaversely to a second point and lowers at said second point to a thread catching position beneath said base upon rotation of said main drive shaft, means mounting a bobbin for rotation at a fixed position under said bed and beneath said needle bar, and in the plane of needle zigzag movement a bobbin shaft mounted for rotation beneath said bed and connected to rotate said bobbin, a crank formed on said main shaft and oriented to throw downwardly when said needle bar is in its said thread catching position, a sliding rod member pivotally connected at one end to said crank, a pendulum formed on said bobbin shaft, means interlocking the other end of said sliding rod member with said pendulum in a manner which permits sliding movement of said sliding rod member along a line radial to the axis of said bobbin shaft, a guide element mounted at a fixed point between said shafts and constructed to constrain said sliding rod member to longitudinal sliding movements through said point whereby rotation of said main drive shaft produces non-uniform rotation of said bobbin shaft, said shafts being realtively rotationally oriented such that said bobbin shaft causes said bobbin to rotate a greater amount during the relatively shorter time said vertical needle is in its aforesaid thread catching position than it does during the relatively longer time said needle is above the surface of said bed.

3. In a zigzag sewing machine the combination comprising: a horizontal bed, a needle bar for mounting a needle in vertical position above said bed, a main drive shaft mounted for rotation above said bed, means for rotating said main drive shaft, a needle bar actuating mechanism interconnecting said main drive shaft and said needle bar, said actuating mechanism being operative to cause said needle bar and needle to move through a zigzag stitching sequence wherein said needle successively and alternately lowers at a first point to a thread catching position beneath said base, raises, moves transversely to a second point and lowers again at said second point to a thread catching position beneath said base upon rotation of said main drive shaft, a bobbin mounted for rotation at a fixed position under said bed and beneath said needle bar in the plane of needle zigzag movement, a bobbin shaft mounted for rotation beneath said bed and connected to rotate said bobbin, a crank formed on said main shaft and oriented to throw downwardly when said needle bar is in its lowermost position, a sliding rod member pivotally connected at one end to said crank, a pendulum formed at one end of said bobbin shaft and grooved along a line radial to the axis of said bobbin shaft, the other end of said sliding rod member having a projecting element which extends into the groove of said pendulum, a guide element pivotally secured to a fixed point between said shafts, said guide element having an opening therethrough accommodating said sliding rod member in slideable relation therewith whereby uniform rotation of said main shaft is converted to non-uniform rotation of said bobbin shaft, said shafts being relatively rotationally oriented such that said bobbin shaft rotates a greater amount during the short time said vertical needle extends under the surface of said bed, than it does during the longer time said needle is above the surface of said bed.

4. In a zigzag sewing machine the combination comprising: a horizontal bed, a needle bar for mounting a needle in vertical position above said bed, a main drive shaft mounted for rotation above said bed, means for rotating said main drive shaft, a needle bar actuating mechanism interconnecting said main drive shaft and said needle bar, said actuating mechanism being operative to cause said needle bar and needle to move through a zigzag stitching sequence wherein said needle successively and alternately lowers at a first point to a thread catching position beneath said base, raises, moves transversely to a second point and lowers at said second point to a thread catching position beneath said base upon rotation of said main drive shaft, means mounting a bobbin to rotate at a fixed position under said bed in a plane passing through said first and second points and beneath said needle bar, a bobbin shaft mounted for rotation in a fixed axial position beneath said bed and connected to rotate said bobbin, and motion transfer means connected to permit said main drive shaft to rotate said bobbin shaft, said motion transfer means incorporating a non-uniform motion conversion means synchronously relating the movements of said needle bar and said bobbin shaft in a manner such that said bobbin shaft rotates through a greater are While said vertical needle is in its aforesaid thread catching positions, and through References Cited by the Examiner UNITED STATES PATENTS 251,195 12/1881 Davis 112189 369,619 9/ 1887 Steward 112--190 447,253 2/ 1891 Mack 112189 577,878 3/1897 Onderdonk 112--190 662,832 11/1900 Spear 112--201 905,488 12/1908 Ammerman 112-189 1,232,263 7/1917 Finch 112-159 10 2,003,879 6/1935 De Spain 112159 2,028,016 1/1936 Schweiger 1l2159 ROBERT V. SLOAN, Primary Examiner.

a lesser arc while said vertical needle is in its aforesaid 15 DAVID J. WILLIAMOWSKY, JORDAN FRANKLIN,

raised positions.

Examiners. 

1. IN A ZIGZAG SEWING MACHINE THE COMBINATION COMARC WHILE SAID VERTICAL NEEDLE IS IN ITS AFORESAID RAISED PRISING: A HORIZONTAL BED, A NEEDLE BAR FOR MOUNTING A NEEDLE IN VERTICAL POSITION ABOVE SAID BED, A MAIN DRIVE SHAFT MOUNTED FOR ROTATION ABOVE SAID BED, MEANS FOR ROTATING SAID MAIN DRIVE SHAFT, A NEEDLE BAR ACTUATING MECHANISM INTERCONNECTING SAID MAIN DRIVE SHAFT AND SAID NEEDLE BAR, SAID ACTUATING MECHANISM BEING OPERATIVE TO CAUSE SAID NEEDLE BAR AND NEEDLE TO MOVE THROUGH A ZIGZAG STITCHING SEQUENCE WHEREIN SAID NEEDLE SUCCESSIVELY AND ALTERNATELY LOWERS AT A FIRST POINT TO A THREAD CATCHING POSITION BENEATH SAID BASE, RAISES, MOVES TRANSVERSELY TO A SECOND POINT AND LOWERS AT SAID SECOND POINT TO A THREAD CATCHING POSITION BENEATH SAID BASE UPON ROTATION OF SAID MAIN DRIVE SHAFT, MEANS MOUNTING A BOBBIN TO ROTATE AT A FIXED POSITION UNDER SAID BED AND AFORESAID THREAD CATCHING POSITIONS, AND THROUGH A LESSER BIN SHAFT IN A MANNER SUCH THAT SAID BOBBIN SHAFT ROTATES THROUGH A GREATER ARC WHILE SAID VERTICAL NEEDLE IS IN ITS BENEATH SAID NEEDLE BAR, AND IN THE PLANE OF NEEDLE ZIGZAG MOVEMENT A BOBBIN SHAFT MOUNTED FOR ROTATION IN A FIXED AXIAL POSITION BENEATH SAID BED AND CONNECTED TO ROTATE SAID BOBBIN, AND MOTION TRANSFER MEANS CONRELATING THE MOVEMENTS OF SAID NEEDLE BAR AND SAID BOBNECTED TO PERMIT SAID MAIN DRIVE SHAFT TO ROTATE SAID A NON-UNIFORM MOTION CONVERSION MEANS SYNCHRONOUSLY BOBBIN SHAFT, SAID MOTION TRANSFER MEANS INCORPORATING POSITIONS. 